Proteins must have a certain degree of purity for commercial applications such as therapeutic and diagnostic uses. Recombinant proteins are typically produced in cultured eukaryotic or prokaryotic cells engineered to express a gene encoding the protein. Expressed proteins are separated from impurities such as unrelated host cell proteins, other host cell components (e.g., DNA, cell membranes, etc.) and media components. Purification techniques such as affinity chromatography, ion exchange chromatography, size exclusion chromatography, hydrophobic interaction chromatography, immobilized metal affinity chromatography, and hydroxyapatite chromatography, separate impurities based on differences in size, charge, solubility, hydrophobicity, and/or affinity for a ligand. It is a struggle for companies in the field of pharmaceuticals to develop purification processes that meet stringent regulatory standards in a cost effective way.